Triruthenium clusters bearing bridging dppm and capping sulfido ligands: X-ray structures of [Ru 3(CO) 6(μ 3-CO)(μ 3-S)(PPh 3)(μ-dppm)] and [Ru 3(CO) 6(μ 3-S) 2(PPh 3)(μ-dppm)

Abstract

Treatment of [Ru 3(CO) 10(μ-dppm)] ( 1) with PPh 3 S at ambient temperature in THF gave the known compound [Ru 3(CO) 7(μ 3-CO)(μ 3-S)(μ-dppm)] ( 2) and the new compound [Ru 3(CO) 6(μ 3-CO)(μ 3-S)(PPh 3)(μ-dppm)] ( 3). Compound 3 can also be prepared by the room temperature reaction of 2 with PPh 3 in the presence of Me 3NO. A similar reaction of [Ru 3(CO) 7(μ 3-S) 2(μ-dppm)] ( 4) with PPh 3 afforded ( 3), [Ru 3(CO) 6(μ 3-S) 2(PPh 3)(μ-dppm)] ( 5) together with the previously reported compound [(μ-H) 2Ru 3(CO) 7(μ 3-S)(μ-dppm)] ( 6). In contrast, a similar treatment of the sulfur-selenium compound [Ru 3(CO) 7(μ 3-S)(μ 3-Se)(μ-dppm)]( 7) with PPh 3 afforded only [Ru 3(CO) 6(μ 3-S)(μ 3-Se)(PPh 3)(μ-dppm)] ( 8). Both compounds 5 and 8 exist as two isomers in solution, arising from the reversible migration of a metal–metal bond, induced by the dppm ligand. The reaction of 6 with PPh 3 under the same conditions gave [(μ-H) 2Ru 3(CO) 6(μ 3-S)(PPh 3)(μ-dppm)] ( 9). Protonation of 4 and 7 by trifluoroacetic acid gave the mono-protonated species [(μ-H)Ru 3(CO) 7(μ 3-S) 2(μ-dppm)] + ( 10) and [(μ-H)Ru 3(CO) 7(μ 3-Se)(μ 3-S)(μ-dppm)] + ( 11), respectively, isolated as their PF 6 salts. All the compounds have been characterized by spectroscopic data together with single crystal X-ray diffraction studies for 3 and 5.